Effective control of blast vibration and flyrock requires that significant factors be identified and quantified, that the blast be designed to ensure both blasting efficiency and compliance with applicable limits, and that the blast design be effectively implemented by field personnel._x000D_
Significant factors contributing to ground vibration and airblast are: charge mass; distance and direction relative to the blast; drilling design: burden, spacing; stemming height and material type; hole diameter and depth; and initiation sequence and direction._x000D_
In addition, airblast may be strongly influenced by shielding and meteorological conditions. Ground vibration is also influenced by the transmission characteristics of the ground and soil. Flyrock throw is determined by charge mass, burden, stemming height, blasthole diameter and depth._x000D_
The contribution of each of the factors has been quantified and models developed to enable the environmental outcomes of blast design to be predicted. Environmental blast design is necessary to ensure compliance with regulatory limits and the implementation of safe' exclusion zones for flyrock clearance._x000D_
This paper discusses the models used for environmental blast design and demonstrates the often significant effects that lapse during implementation of the design can have on predicted outcomes._x000D_
In practice, drillers and shotfirers are sometimes confronted with situations that require modifications to the blast design to cope with the real site situation._x000D_
Methods are presented that may be used by drillers and shotfirers to evaluate the effect of these modifications, the tolerances that must be reached during their work practice and checking procedures, and the consequences of their actions.